This invention relates to the construction of an articulated hemispherical dome which is primarily intended for use as an observatory roof that may be opened to any degree desired, such as from a slit to a fully exposed hemisphere in order to view the sky. When the dome is fully closed, the dome forms a weather-tight roof to protect the observer and his equipment.
The concept of a folding or collapsible building or roof has been with us for some time. Many variations on this particular theme exist as prior art to this: invention. These variations fall into two main categories: collapsible structures covered with rigid sheathing; and collapsible framed structures with fabric coverings.
Examples of the first category of folding systems can be seen by examining the following art: U.S. Pat. No. 1,572,790, dated Feb. 9, 1926, titled "Garage" by H. S. Grigsby. Mr. Grigsby presents a two-piece, folding, hemispherically-shaped building made up of sections of sheet metal arches which are rigidly secured to a curved metal frame that defines its shape. The metal arches are further pivotal along a common horizontal axis. Half of this particular structure can be opened at a time to allow a vehicle to pass into and if desired, through the building. A further refinement to Mr. Grigsby's invention is the "Folding, Collapsible, Portable Building" represented in the U.S. Pat. No. 2,728,115, dated Dec. 27, 1995, by G. Cornelius. This structure is a complex but versatile building in a semi-cylindrical shape with extendible, overlapping, transversely curved rigid roof sections held in position by semi-circular end walls which are pivotal along a common horizontal axis, but also hinged along one outer longitudinal edge. Cornelius's building allowed access at ground level to the entire interior of the structure, and then was able to close the structure into a weather-tight housing. A third and even more complex example of a folding roof can be found in U.S. Pat. Nos. 4,995,203 and 5,070,659, authored on Feb. 26, 1991, and Dec. 10, 1991, respectively, by Brisbin, et al., titled "Retractable Roof for Stadium Structure". These patents feature an amazingly complex and specific stadium roof composed of two opposing, rigid, overlapping roof assemblies on separate pivot mechanisms, which through a system of weighted floats in liquid reservoirs, pulleys, cables and hydraulics allow the roof sections to be opened, closed, or to be maintained in an intermediate position. This structure also requires a complex foundation for support.
The second category of folding structures, those with fabric coverings, are typically constructed of one or more layers of fabric stretched over multiple rigid frame members, the frame members being pivotal and the fabric acting to weatherproof the building and to maintain the spacing of the frame members when the structure is closed. Variations on this theme can be seen in the following art.: U.S. Pat. No. 4,583,331, by Hunt et al., dated Apr. 22, 1986, titled "Frame Supported Structure with Tensioned Fabric Panels"; U.S. Pat. No. 4,833,837, by Bonnea, dated May 30, 1989, titled "Folding Radome"; and U.S. Pat. No. 5,004,001, by Bouchard, dated Apr. 2, 1991, titled "Foldable Dome".
The available prior art depicting folding and collapsible structures share similar disadvantages for the builder when compared to the present invention to be described hereinafter. These disadvantages include: a dependence on an internal framework to support the structure; radiused, flanged interlocking parts that are difficult to manufacture; complex operating mechanisms; a necessary understanding, talent and expertise in a variety of arts including training in advanced engineering disciplines and mathematics to construct and operate the devices; as well as extensive tooling requirements for fabrication of the structures.
The motivations that inspired the present invention of an "Articulated Dome" include the desire to create a structure that fulfilled the requirements of protection and access necessary for an observatory roof, and simple enough in design to be built by anyone with a basic knowledge of mathematics, familiarity with basic hand tools (or simple power tools if available), and access to common materials available at the local level.